The present invention relates to a storage system comprising a plurality of storage devices.
A storage system comprises, for example, a plurality of storage devices, a controller for controlling the access from an upper-level device to each storage device, and switch devices introduced between the controller and a plurality of storage devices. Such storage system is disclosed in Japanese Patent Applications Laid-open No. 2004-145497 and 2003-280824. These applications disclose the connection between a plurality of controllers provided in a plurality of storage systems.
There are also types of storage systems in which, for example, the number of storage device units comprising switch devices and a plurality of storage devices can be increased or decreased. More specifically, in addition to a communication port (referred to hereinbelow as “upstream port”) for connection to an upper-level device, the controller comprises a plurality of communication ports (referred to hereinbelow as “downstream ports”) for connection to storage device units, and the switch device of the storage device unit comprises a plurality of communication ports (referred to hereinbelow as “switch ports”). A switch port of the switch device of the storage device unit is connected to at least one of a plurality of the downstream ports of the controller. The controller, storage device, or another switch device is connected to the switch port.
If physical connection is performed according to the predetermined rule (for example, SAS code (the rule of SAS (Serial Attached SCSI)) or FC code (the rule of FC (Fiber Channel))), there sometimes appear a communication port for which the physical connection is not required, that is, a free port. More specifically, the respective free ports are sometimes present in both the controller and the storage device unit and the respective free ports are sometimes present in two storage device units, but are not present in the controller.
It is desirable that the free ports be used effectively, but the technology therefor cannot be derived from the aforementioned Japanese Patent Applications Laid-open No. 2004-145497 and 2003-280824. This is because Japanese Patent Applications Laid-open No. 2004-145497 and 2003-280824 relate, as mentioned hereinabove, to a technology for mutually connecting a plurality of controllers provided in a plurality of storage systems and do not relate to connecting a controller and a storage device unit.